Power-transmission apparatus



March 31, 1931. H. B. CHALMERS POWER TRANSMISSION APPARATUS Filed April2. 1925 2 Sheets-Sheet l March 31, 1931. CHALMERS 1,798,723

POWER TRANSMI S S ION APPARATUS Filed April 2, 1925 2 Sheets-Sheet 2Patented Mar. 31, 1931 PATENT caries HEN-RY B. GHALMERS, oFNEW YORK, N.Y.

POWER-TRANSMISSION APPARATUS- Application filed April 2,

The main obje'ct of my invention isto'vary the transmitted speedinversely With theload. In general it is also useful henever the drivenmember is to carry a variable load or the driving memher is a variablepower, as a windmill. It is applicable to many uses, such asthe drivingor'punching and shearing presses, lathes and other machine tools, aswell as fer the driving of motor vehicles. It

1') is also very useful for utilizingiaconstant speed A. C. motor for avariable load.

It has been proposed to utilize the inertia of oscillating massesconnected between driving and driven members, but the unbalanced forceof vihraition incident to such oscillation render such' devices highly"obj ec'ti'onable. I'propose,- 01r the contrary, toutiliz'e' thewellknownprinciple of inertia of an ordinary rotating' fly wheel butdiflerentially'mounted between the driving and driven memhers so that itmay simultaneously a-hsorhpower from one member and give up power to theother.

Ordinarily, of course, the fly Wheel can not be both absorbing anddelivering power at the same instant, but by mounting it differentiallywith respect to the driving a-nd driven members we areab'le to varyits'velocity at definite rates inverselywith the velocity of saidmembers so that the transmitted speed varies inversely with the load.Fig. I shows in section and the elements of a simple-apparatusillustratingthe principle of theinvention;

Fig. 2 is a side view of the same;

Fig. 3 is a purely diagrammatic view-illustrating the relative movementsof the elelllGIlljS of the mechanism shown in Figs. 1

and? H Fig. l is aview similar to Figl'l of a partially balancedmechanism.

Figs; 5 and 6 are end and side views, respectively, showing parts insection-of a more fully developed form of apparatus-embodying theinvention, the parts being" substan- -t ia'lly'balan'ced as toacceleration and retardation and balanced as to'gravity and centrifugalforce".

The construction and mode of operation of the apparatus in Figs. 5 and 6will he more readily understood from astudy oftheparts end elevation1925. Serial no, 20,1471

illiistrated in Figs; 1' and'Q an'dthe diagram of Fig; 3; In Figs. 1and'2, 10 and 11 represent the'drivin g and driven members,respectively; I Power-is applied to-the shaft memher I 10 and the workis performed by or from the'shait 1'1. Itwill be understood, of course,that thememh'erslt) and are supportedin suitable bearings. The drivingmember" 1 0' is provided with a crank arm" 12 adapted to rotatewith it.The driven member 1 1 also has a crank arm 13 which servesto rotate it;fhe inertia mass 14; is connected tothecranl: arms 12 and 1 3 bylinks-15 and I6, respectively, in such a manner as to permit the twocranks 12 and 13 to rotate together or independently. In this particular"instance the links 15ancl1 6 are both shown as connected to the bearingpin 17.

If we consider the driven shaft I1- and its crank arm 13 as:stationaryand rotate the d'rivingshaft- 10 andits crank arm-112 in aclockwise direction, it Willbe seer; that the arm 12 in its rotationWill carry With it; the

' inner end of the link 1 5- and thus compel the mass 14' to travel theare of acircle about the inner emf of the crank 16; If we: consi'der'the angular Velocity of the crank 12' to be constant, asit would be with"a constantly applied force, then it will be obvious that the angularvelocity ofthe mass'l 't' about the pin 19 mustpnecessarily be variable;In Fig- 3 I: have shown a dot-and-dash circle as representing" the: pathof the center of the connecting pin 18" as it'travels around the centerof theshaift IO, and I have shown by d'o t-and -das'h lines the path 210f the center of the pin 17" which is the approximate center of the mass14. The circle 20" is divided into equa-P partsrepresenting equalperiods of timeintheconstantangular speed of the shaft 10 i The lengthof the cranks and links being fixed, it Will be seen" that the pin 17necessarily travels at a variable speed which, fromtheposition showninFig. 3, decreases from the position shown as the parts rotateclockwiseuntil it" gets to the point S near the b'ottom ofthe figure, atwhich its angular velocityabo'ut the center 19 is the minimum; From thispoint o'n ,*as the mass continues to rotate around the" center 19, theangular velocity increases until it reaches the point F at which itsangular velocity is the maximum. As the mass passes from the point F atits maximum speed right-handed toward the point S, it is being retardedor decelerated and places the link 15 in compression. \Vhen the mass 14passes the point p S traveling right-handed, power is applied to itthrough the link 15, which is now in tension, while the mass 14 is beingaccelerated toward the point F. .iIt willbenotedithat during theacceleration of the mass, its resistance to such accelerationtends topull the link 15 in a counter-clockwise direction around theinstantaneous center, namely, pin 18, and therefore the resultant ofthis pull is a compression in the link'16 and a pressure on the pin 19in a clockwise direction producing a torque on the driven member. On theotherhand, when the mass 14 isbcing retarded, its tendency to continueat the same velocity puts the link 15 in compression and tends to rotateitabout the instantaneous center, namely, the pin 18, thus putting link16 into tension and producing a torque on driven shaft 11. It will benoted that this torque on a driven shaft 11 is always in the directionthat the driving shaft 10 is moved, except for a very small portion ofthe travel of the mass between Ftand the points on its path crossed by aplane through 10, 11, and 19, but this reversal of pull is very slightowing to the fact that the velocity of the mass is nearly constant closeto the point F. The same condition exists adjacent the slowest point S.This condition is dependent upon the relative dimensions of the linksand cranks. q

It will be observed in Figs. 1 and 2 as shown in the elementary form ofthe invention, that the gravitational force as well as the centrif ugalforce, operate here to cause vibration trouble. Both these causes can beeliminated by continuing the link 16 in the opposite direction an equaldistance, as shown in Fig. 4, and mounting on its end a weight 14' tobalance the weight 14 plus a portion of the weight of the link 15. Itwill be observed that an improved form of 't-he invention would be toenlarge the weights 14 and 14 by describing them in a circle about 19.as ,a

center to form a fly wheel rim and adding other suitable arms thereto,.Two such :fly wheels are shown in Figs. 5 6. In this form 22 representsthe driving member and 23 is the driven member. I In this case there aretwo masses, 24 and 25, in the form of fly wheels mounted on crankbearings26 and 27 which are formed as parts of or connected to the shaft23. The arm'28 in this case corresponds with the arm 13 in Fig.1, andsimilarly the arm 29 constitutes the crank arm for the fly wheelcorresponding to thearm 1 3.

For convenience in; construction the end- 30 o e e 2 ha wea n ri e,member 22 or concentric with it. The crank pin 27 is connected with theend 30 by a crank arm 31. A casing 32 forms a part of the driving memberand contains the fly wheels and the means connecting the fly Wheels withthe crank shaft 23. A bracket 33 is secured inside this casing in anysuitable manner, as for instance, by bolts 34. 1 Thisbracket has abearing for the pin 35 'onone end of the link 36. The other end of thislink 36 is hinged on the pin 37 which projects from the rim of the flywheel 25. The casing 32 and bracket 33 correspond with the crank arm 12of Fig. 1, and the pin 35 corresponds with the pin 18. Link 36corresponds with link 15, andpin37 corresponds with pin 17. The flywheel 25 may be provided with a counterweight 38 to counter-balance themass of the pin 37 and part of the link 36., It will thus be seen thatit is possible to approximately balance the fly wheel 25 and itsattached parts with respect to centrifugal force around, the axis of thecrank pin 27. t f

To prevent a twisting strain on pins 35 and 3.7, I preferablyprovide apin 39 whose axis isin line with the pin 35 and connected by alinkv40-to the pin 37. To counterbalance the weightof the bracket 33 andattached parts, I may provide a weight 41 in theopposite side of thecasing 32.

Thefly wheel 24, being arranged on an axis 180 away from the axis of thefly wheel 25, counter-balances the local inertia forces set up in thedriven member. This fly wheel.24

is connected to the casing through the medium of a bracket33 and thedouble connect- I inglinks 42. It will be understood, of course,

that the casing 32 may be filled with grease or other lubricant and thatthe bearings shown are merely diagrammatic representations. For thepurpose ofpermitting the fly wheel 25 to be applied or removed, I mayform the-bearing on the pin 27 of parts 43 and 44 held together by bolts45 which-pass through the hub ofcthe fly wheel. By loosening the. bolts45, the fly wheel may be slipped. along the "crank shaft sufliciently torelease thebearings-43 and 44 and permit them to be removed. I

I'claim:

1. Power. transmission mechanism comprising a casing, a shaft, revolublewith respectto said casing and having oppositely V disposed ofisetbearings, a fly wheel mounted on' each of said bearings and means ofconnection between the said fly wheels and said casing comprisingconnected arms pivotally supportedby said casing'and connectedres'pectively to said flywheels.

12. A driving member and a'driven member,

acrank connectedto and rotatablewith each member and a two-part hingedmember connecting the two cranks,-said two-part hinged member includinga plurality of v-completely t a efiywhe 3. Power transmission mechanismcomprising driving and driven members, said driven member having offsetcranks, fly Wheels revolubly mounted on said cranks, a bracket revolublycarried by said driving member eccentric to the axis thereof, andoppositely disposed offset cranks supported in said bracket andconnected to said fly wheels respectively.

HENRY B. CHALMERS.

